Object processing involves the integration of many sources of information into a single perception or judgment. Both behavioral and neuroscientific studies have demonstrated attentional modulation of object processing: judgments about an object depend on attributes attended to. The proposed studies will investigate the neural bases of this attentional modulation. First, object processing in an attribute judgment task will be examined for different object categories, as established by behavioral research, using functional imaging techniques. Patterns of brain activation will be recorded for four different object categories in both attended and non-attended conditions. Epoch- averaging analyses will reveal components of attentional modulation that are common to all object types and aspects of modulation that depend on the type of object being judged. Second, an event-related analysis technique will be developed. This technique will allow investigation of single-trial attentional effects on object judgments. Investigation of attentional processes will benefit research into clinical syndromes characterized by impaired attentional processing (e.g., schizophrenia, attention-deficit disorder). The current studies will provide a description of the attentional systems in the brain underlying object perception. An understanding of these attentional systems will generate research hypotheses for work with patient populations.